The Inscribed Polygon Method for Predicting Aromaticity

To fill the MOs, the six electrons are added, two to an orbital, beginning with the lowest energy orbital. As a result, the six electrons completely fill the bonding MOs, leaving the antibonding MOs empty. This is what gives benzene and other aromatic compounds their special stability and this is why six % electrons satisfies Hiickel s 4n + 2 rule. 

An inscribed poiygon is aiso caiied a Frost circle. 

HOW TO Use the Inscribed Polygon Method to Determine the Relative Energies of MOs for Cyclic, Completely Conjugated Compounds 

Step [1] Draw the polygon in question inside a circle with its vertices touching the circle and one of the vertices pointing down. Mark the points at which the polygon intersects the circle. 

Step [2] Draw a line horizontally through the center of the circle and label MOs as bonding, nonbonding, or antibonding. 

Step [3] Add the electrons, beginning with the lowest energy MO. 

Using the inscribed polygon method for five- and seven-membered rings 

---